Device for producing mechanical energy

ABSTRACT

The invention relates to a device for producing mechanical energy. Said device contains an internal combustion engine and an expansion engine ( 20, 21 ) which is fed with superheated steam from a steam generator. Exhaust gases of the internal combustion engine are injected into the steam generator ( 24 ) to use the waste heat thereof. In order to eliminate pollutants and non-burned fuel in the exhaust gases of the internal combustion engine in a simple and effective manner, the steam generator ( 24 ) is heated by a non-catalytic burner ( 16 ) at a burner temperature of between 1100° and 1300° C. The exhaust gases of the internal combustion engine can be combined with the combustion gases in the burner ( 16 ). The after-burning of non-burned fuel and the combustion of pollutants is thus carried out in a burner ( 16 ) in a non-catalytic manner. The combustion gases in said burner ( 16 ) are at a temperature such that non-burned fuel components in the exhaust gases of the internal combustion engine which are introduced into the burner are after-burned, but form, however, essentially no nitrogen oxides at excessive temperatures. The burner ( 16 ) is used to heat the steam generator ( 24 ) and can be designed according to the energy requirement of the steam generator ( 24 ) and the expansion engine ( 20, 21 ). The heat of the exhaust gases of the internal combustion engine is used to generate steam.

TECHNICAL FIELD

[0001] The invention relates to a device for the generation ofmechanical energy comprising an internal combustion engine and anexpansion engine which is fed with superheated steam from a steamgenerator, wherein the exhaust gases of the internal combustion engineare injected into the steam generator to use the waste heat thereof.

PRIOR ART

[0002] The DE 196 10 382 C2 describes a combined engine consisting of acombustion engine and an expansion engine in the form of a steam engine.The steam engine receives the high pressure steam from a steamgenerator. The high pressure steam is preheated by the cooler of theengine block of the combustion engine. The steam generator is exposed tothe exhaust gases of the combustion engine. the combustion engine andthe steam engine operate on a common crank shaft. In order to filterpollutants from the exhaust gases an oxidizing catalytic converter isarranged upstream of the steam generator in the exhaust pipe which isguided through the steam generator to the atmosphere. The DE 196 10 382C2 suggests to insert fuel from time to time or continuously into theexhaust pipe upstream of the catalytic converter to increase the portionof the power of the steam engine. This additional fuel is burnt in thecatalytic converter together with unburnt fuel from the combustionengine.

[0003] This is an after-burning of unburnt fuel from the combustionengine by an oxidizing catalytic converter in the usual way. The steamgenerator primarily uses the waste heat of the exhaust gases includingthe combustion heat generated in the oxidizing catalytic converter.Additionally fuel can be injected into the oxidizing catalytic converteronly to increase the power of the steam generator still more.

[0004] The amount of fuel which can be additionally burnt in theoxidizing catalytic converter is limited by the constructive propertiesof the oxidizing catalytic converter. The oxidizing catalytic converteris designed to after-burn the remnants of unburnt fuel in the exhaustgases or certain pollutants, but not to serve as the heat source for asteam generator. The steam engine operating on the same crank shaft asthe combustion engine essentially is to make use of the heat of theexhaust gases and thereby increase the efficiency.

DISCLOSUE OF THE INVENTION

[0005] It is an object of the invention to increase the power of thesteam generator with a device of the above mentioned kind.

[0006] It is a further object of the invention to eliminate pollutantsand unburnt fuel form the exhaust gases of the combustion engine in asimple and effective way.

[0007] According to the invention this object is achieved in that thesteam generator is heated by a non-catalytic burner to a burnertemperature between 1100° to 1300° C. and the exhaust gases from thecombustion engine are injected into the combustion gases of the burner.

[0008] The after-burning of unburnt fuel and the combustion ofpollutants is therefore effected in a non-catalytical manner in aburner. The burning gases in this burner have such a temperature that,on one hand, unburnt fuel components in the exhaust gases of thecombustion engine supplied thereto are after-burnt and, on the otherhand, essentially do not form any nitrogen oxides due to hightemperatures. The burner serves for heating of the steam generator andcan be designed in accordance with the power requirements of the steamgenerator and the expansion engine. The heat of the exhaust gases of thecombustion engine is used for the steam generation.

[0009] The non-catalytical burner can be a porous burner. Preferably thenon-catalytical burner and the combustion engine are operated with thesame kind of fuel.

[0010] Preferably the burner is arranged downstream to a mixing chamber,into which the hot exhaust gases of the combustion engine are injected.Fuel is injected into the hot exhaust gases for the generation of aburning gas for the burner. The hot exhaust gases are used to evaporatethe fuel and to generate a burning gas in the mixing chamber.

[0011] Preferably the burner is provided with air supplying means. Theair supplying means can introduce combustion air into an exhaust pipeupstream from its opening into the mixing chamber. The air supplyingmeans can be provided with a fan. Upstream from the junction of the airsupplying pipe and the exhaust pipe a sensor can be arranged for thedetermination of the oxygen content in the exhaust gas. The fan can thenbe controlled depending on the oxygen content.

[0012] Downstream from the burner a catalytic converter for pollutantsor a carbon-particulate filter or both can be provided. The catalyticconverter for pollutants and the carbon-particulate filter are arrangedupstream from the steam generator.

[0013] The remains of pollutants which are not yet burnt by the burneror which have formed in the burner, for example in the form of nitrogenoxides, are burnt in such a downstream catalytic converter forpollutants. The catalytic converter for pollutants only needs to bedesigned for burning the remainder of pollutants. The catalyticconverter for pollutants is quickly heated up by the hot exhaust gasesfrom the burner which have not been cooled down by the steam generator.Also the for example ceramic carbon-particulate filter is heated suchthat the carbon particles are burnt therein.

[0014] An embodiment of the invention is described in greater detailhereinbelow with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a schematical side view of a combustion engine withexhaust pipe and an integrated steam engine as an expansion engine.

[0016] FIG.2 is a more detailed, but schematic representation of thesteam engine of FIG.1.

[0017] As a combustion engine, FIG. 1 shows a typical piston engine 1with a engine block 2, a cylinder head 3 and an oil pan 4 therebelow.The piston engine 1 is provided with five cylinders, the outlet of eachof the cylinders opening into an exhaust manifold 6- to 10. The exhaustmanifolds 6 to 10 end in a collector 11 joining to a main exhaust pipe12. The main exhaust pipe 12 is provided with an extension 13 wherein anexpansion engine is incorporated in the form of a steam engine of thekind shown in FIG. 2 in greater detail.

[0018] As can be seen from FIG. 2 the main exhaust pipe 12 opens into aburner device 14. The burner device 14 is arranged coaxial to the mainexhaust pipe 12. The burner device 14 is provided with a mixing chamber15, on the entrance side, and with a burner 16 in the form of a porousburner downstream thereof. As is well known, a porous burner is providedwith a burner body made of porous ceramic material. A fuel gas-air-mixis burnt in the porous burner body without open flame, the flame frontextending within the porous burner body. Exhaust gases leave the burnerbody as combustion products. However, the described device can operatewith different suitable burners.

[0019] Fuel is injected into the mixing chamber 15 by fuel injectingmeans 17. This fuel is of the same kind as that fed to the piston engine1. The injected fuel is mixed with the hot exhaust gases of the pistonengine and is, thereby, evaporated. The mixture is burnt in the burner16 with a very homogenous temperature distribution at between 1200 and1300° C.

[0020] A catalytic converter for pollutants 18, which may be a simpleoxidizing catalytic converter is directly and axially arrangeddownstream of the burner device 14. Due to the direct connection thecatalytic converter for pollutants 18 is heated up extremely fast afterthe starting so that only little starting emissions are generated. Ifthe piston engine 1 is a diesel engine a carbon-particulate filter, forexample on the basis of ceramics, replaces the catalytic converter forpollutants 18. Due to the directly connected burner device 14 arrangedupstream the carbon-particulate filter can be heated very much, suchthat the carbon particles are burnt and the carbon-particulate filter iscleaned out.

[0021] A steam engine 19 also is arranged adjacent and coaxial and isprovided with a first expansion stage 20 and a second expansion stage21. They are connected to a coaxial drive shaft 22 outside of theexhaust pipe which drives a generator 23 for the generation of electricpower either for directly supplying electric consumers or for a carbattery. Instead, auxiliary power units such as the compressor of an airconditioning system can be driven directly.

[0022] The second expansion stage 21 is surrounded by a first steamgenerator 24 which is provided with an annular heat exchanger not shownin detail, through which the heating gas generated by the burner device14 flows. In the first steam generator 24 flows feed water coming from afeed water pre-heater not shown in detail. It flows to a second steamgenerator 25 surrounding the first expansion stage 20 and also beingexposed to the heating gas generated in the burner device 14. The steamgenerated in this way is expanded in the first expansion stage 20 to amedian pressure. After the first expansion, the steam is heated tohigher temperature again in the re-heater 26 and expanded to a lowpressure in the subsequent second expansion stage 21. Afterwards thesteam is lead to a condenser in a closed system not shown in detail. Inthe condenser the steam is completely condensed to feed water. The feedwater is then returned to a reservoir. The technically useable power isrealised in the two expansion stages 20, 21. Due to the re-heating, highefficiency is achieved.

[0023] Such closed systems are known (DE-Z “MTZ MotortechnischeZeitschrift”, 61 (2000) 314-323) and are therefore not described here indetail. Also the re-heater 26 is exposed to the axial flow of heatinggas. The re-heater jacket-like surrounds the two expansion stages 20,21. Thereafter the heating gas re-enters the main exhaust pipe 12 whichcontinues with a decreased diameter.

[0024] If the piston engine 1 is a diesel engine, the excess air in theexhaust gas is sufficient to maintain the combustion in the burnerdevice 14. In Otto engines the amount of this excess air is—if there isany at all—too small. In this case an air supply device 27 is providedconsisting of an air filter 28 on its entrance-side and an electricallydriven fan 29. The air supply device 27 is connected to the main exhaustpipe 12 by an air supply pipe 30 joining the main exhaust pipe. Therebyexhaust gas with an increased amount of air flows into the mixingchamber 15. In order to achieve a complete combustion a sensorresponsive to oxygen, for example a lambda probe, is provided in frontof the junction of the air supply pipe and the main exhaust gas pipe 30,the probe measuring the oxygen contents in the exhaust gas. The airsupply is controlled by the fan depending on this oxygen contents.

1-10. (cancelled)
 11. A device for generating mechanical energy comprising an internal combustion engine providing hot exhaust gases, and an expansion steam engine, a steam generator and means for feeding steam from said steam generator to said expansion steam engine, non-catalytic burner means operating at temperatures between 1100° C. and 1300° C. for heating said steam generator, means for supplying fuel to said non-catalytic burner means, and means for injecting said exhaust gases from said internal combustion engine into said fuel supplied to said burner means.
 12. A device as claimed in claim 11, wherein said non-catalytic burner means comprise a porous burner.
 13. A device as claimed in claim 11, wherein said non-catalytic burner means and said combustion engine are operated with the same kind of fuel.
 14. A device as claimed in claim 11, wherein said non-catalytic burner means comprise a non-catalytic burner and mixing chamber means arranged upstream of said non-catalytic burner, means for feeding said hot exhaust gases from said internal combustion engine through exhaust pipe means opening into said mixing chamber means and means for injecting liquid fuel into said hot exhaust gases, whereby said liquid fuel is evaporated and, together with said hot exhaust gases provides combustion gas for said non-catalytic burner means.
 15. A device as claimed in claim 14, and further comprising means for supplying air to said non-catalytic burner means.
 16. A device as claimed in claim 15, wherein said air supplying means comprise an air supply pipe, said air supply pipe into said exhaust pipe means upstream of said opening of said exhaust pipe means into said mixing chamber means.
 17. A device as claimed in claim 16, wherein said air supplying means comprise fan means for feeding air into said air supply pipe and sensor means for determining the oxygen contents in said exhaust gases, and means responsive to said sensor means for controlling said fan means.
 18. A device as claimed in claim 11, wherein a catalytic converter for pollutants is provided downstream of said non-catalytic burner means.
 19. A device as claimed in claim 11, wherein a carbon-particulate filter is provided downstream of said non-catalytic burner means.
 20. A device as claimed in claim 18, wherein said catalytic converter for pollutants is provided upstream of said steam generator.
 21. A device as claimed in claim 19, wherein a carbon-particulate filter is provided upstream of said steam generator. 